U.S. Pat. No. 6,535,281, titled “Method and apparatus for optically scanning a vehicle wheel,” discusses a method an apparatus for scanning a motor vehicle wheel with an optical scanning device for the detecting geometrical wheel data. The entire disclosure of the patent is incorporated herein by reference. During calculation of the angular position and the size of the balancing weights to be fitted in the balancing planes, the required geometrical wheel data are evaluated.
Another U.S. Pat. No. 6,122,957, entitled “Wheel-balancing method and device,” discusses a method for ascertaining the contour of the rim during a wheel balancing process, and for determining optimum balancing positions for balancing weights based on the contour and the size of the balancing weights from the measurement results of the unbalance measuring operation. The entire disclosure of the patent is incorporated herein by reference.
U.S. Pat. No. 5,189,912, entitled “Ultrasonic wheel measuring apparatus and wheel balancer incorporating same,” discusses a method for determining the type of standardised motor vehicle wheels based on scanned geometry data, and determining the associated axial positions for fitting balancing weights. The entire disclosure of the patent is incorporated herein by reference.
This disclosure describes an improved method and apparatus for balancing a wheel, by which positions suited to types of rim or types of wheel for fixing balancing weights are determined.
According to one embodiment, contour features of the rim surface to which balancing weights can be fixed are detected. The detected contour features are compared to stored contours or contour features of a plurality of types of rims or types of wheels. Balancing planes that are suitable for those stored types of rims or wheels, or regions in which the balancing planes can be found, are predetermined. Based on the comparison result, at least one balancing plane of the type of rims or wheels that has the best match with the motor vehicle wheel corresponding to the contour or contour features of the rim surface can be determined. Based on the determined balancing plane or planes, the angular position and size of the balancing weight or weights are calculated, derived from the measurement values obtained in the unbalance measuring operation.
Relevant contour features of the rim of a motor vehicle wheel include flat surface portions, rim surface portions extending in parallel relationship with the axis of the wheel, parts of the rim surface adjacent to the wheel disc portion or to the spokes of the wheel, and rim flanges. Those rim surface portions are suitable for fixing balancing weights. The at least one balancing plane is disposed within those surface portions. For a dynamic balancing procedure, two balancing planes are determined in those surface portions; while for a static balancing procedure, it is sufficient to determine only one balancing plane. In one embodiment, adhesive weights are fixed in the flat surface portions, in particular surface portions extending in parallel relationship with the axis of the wheel. Clip-type weights may also be used to attach to the rim flanges.
According to another embodiment, when determining the type of rims or wheels, determination of contour features that are not suitable for fixing balancing weights is also made. Contour features that are not suitable for fixing balancing weights include steps in the rim surface or surface portions, which extend inclinedly or approximately perpendicularly to the axis of the wheel.
According to still another embodiment, in determination of the contour features, the spacing of the respective contour features from a reference plane or a reference point on the balancing machine are determined by a scanning device. During determination of the type of rim or wheel, additional parameters, such as the rim material (steel or aluminium), the rim width, the rim diameter and the wheel diameter, are determined by the scanning device. Examples of optical scanning devices are described in, for example, U.S. Pat. No. 6,535,281, entitled “METHOD AND APPARATUS FOR OPTICALLY SCANNING A VEHICLE WHEEL,” the entire disclosure of which is incorporated herein by reference. According to one embodiment, three optical scanning devices are used, wherein a scanning device is provided for scanning the inside of the wheel, the outside of the wheel, and the wheel peripheral running surface, respectively. A laser beam is used for the scanning operation.
The optical scanning beam can further serve for marking the balancing positions when the wheel to be balanced is moved into the appropriate angular position. In that case, a change in the axial position of one or both balancing planes can be implemented by the optical scanning beam being displaced or pivoted. In that case, the point of impingement of the optical scanning beam lies in the corrected balancing plane. That modification can be effected by the operator. An evaluation device of the balancing machine then re-calculates the angular position and size of the balancing weight, for the new balancing plane. It is possible to provide optimum positioning of the balancing weight on the surface of the rim.
The data related to the detected contour features or the contour of the rim are stored with the geometrical data with respect to the axial position of the at least one associated balancing plane. If, for example, a set of four vehicle wheels of a motor vehicle is to be balanced, the stored data can be used for the subsequent balancing operations on that set of motor vehicle wheels. In addition, the stored data can be used for improved representation of the types of rim or wheel for implementing a learning process for the storage and calculating system in the evaluation device. The data can be used to balance other vehicle wheels of the same or a similar type. The learning process is advantageous, particularly in relation to light metal or alloy wheels such as aluminium wheels with a wide range of types.
Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only exemplary embodiments of the present disclosure is shown and described, simply by way of illustration of the best mode contemplated for carrying out the present disclosure. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.